1. Technology Field
The invention relates to a data processing method. More particularly, the invention relates to a data processing method for a rewritable non-volatile memory module, a memory storage device using the data processing method, and a memory control circuit unit using the data processing method.
2. Description of Related Art
The markets of digital cameras, mobile phones, and MP3 players have expanded rapidly in recent years, resulting in escalating demands of consumers for storage media. Since a rewritable non-volatile memory module (e.g., a flash memory) is characterized by data non-volatility, low power consumption, small volume, non-mechanical structure, and so on, the rewritable non-volatile memory module is rather adapted to be built in a variety of portable multimedia devices.
In most cases, the rewritable non-volatile memory module is employed together with a host system. The host system is able to access data in the rewritable non-volatile memory module, i.e., the host system is able to read data from or write data into the rewritable non-volatile memory module. Under certain circumstances, the data written into the rewritable non-volatile memory module are encrypted first, and the data read from the rewritable non-volatile memory, module are decrypted first and then transmitted to the host system. Said encryption and decryption operations may be performed by means of a circuit which encrypts the data from the host system and decrypts the data to be transmitted to the host system. However, the rewritable non-volatile memory module has the smallest unit (e.g., a physical page) for writing data. If the amount of data to be written by the host system is smaller than the capacity of one physical page, said physical page will be filled with specific data. In consideration of consistency in encryption and decryption algorithms, the specific data need be encrypted. Since additional circuits are required for encrypting these specific data, the manufacturing costs may increase due to the additional circuits.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the invention, or that any reference forms a part of the common general knowledge in the art.